The present invention relates to a stripping composition for paints, varnishes or lacquers covering a substrate.
Strippers for paints and varnishes or lacquers are employed in two ways: by deposition or by immersion. The strippers applied by deposition are generally applied by brushing or spraying. They almost always contain a thickener and are employed at ambient temperature (20.degree. C.). They are employed for small tasks or for objects to be stripped which cannot be immersed. This category includes stripping by the general public, professional stripping in the building trade and aeronautical stripping. The strippers using immersion employ either cold baths (often based on methylene chloride) or hot baths (often based on caustic soda). They are employed above all for the stripping of a large number of small articles (industrial stripping).
A stripping composition including, by volume, from 1 to 20% of a polar aprotic solvent such as dimethyl sulphoxide, (DMSO) or N-methylpyrrolidinone (NMP), and from 99 to 80% of an ether such as tetrahydrofuran is already known from EP 0 490 726.
A stripping composition including, by volume, from 1 to 20% of a polar aprotic solvent like DMSO and NMP and from 99 to 80% of an ether exhibiting a flash point higher than 0.degree. C., a molecular volume smaller than 160 and a molecule provided with one or more methoxy groups is already known from EP 0573 339; this ether may be especially anisole.
Although very efficient in their stripping action, these two stripping compositions above have, nevertheless, the disadvantage of being costly.
Furthermore, WO 93/07227 discloses the addition of water to solvents or to solvent mixtures considered to be efficacious in paint stripping. This document describes compositions containing 1) at least one organic solvent chosen from ethyl acetate, methyl ethyl ketone and toluene, 2) water, 3) at least one thickener and 4) at least one surfactant.
The effectiveness of these compositions is simply proportional to the quantity of organic solvent employed and, in any way, is lower than the effectiveness of the pure solvent.
There is thus a need in the stripper industry to find other compositions whose cost is lower, but which are at least as effective as the compositions of the prior art.